Electron discharge device



April 6, 1948. D. B. LANGMUIR ELECTRON DISCHARGE DEVICE Filed Aug. 12, 1945 2 Sheets-Sheet l l VENTOR DHVID Blnnamuln 422% ATTORNEY Patented Apr. 6, 1948 ELECTRON DISCHARGE DEVICE David B. Langmuir, Englewood, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application August 12, 1943, Serial No. 498,271

Claims. (Cl. 250-27.5)

My invention relates to electron discharge devices particularly useful at ultra high frequencies and associated circuit elements.

Broadly, the electrode elements utilized in electron discharge devices for use at high frequencies must be small and closely spaced to reduce the inductance of the electrodes and leads as well as the interelectrode capacities so that the device may operate at the high frequencies. On the other hand, in order to obtain high power output, electron discharge devices must be able to dissipate large amounts of power and heat. In devices of this kind, problems involving seals, circuits and assembly of the electrode mounts must be solved with other than conventional structures.

In more detail the more important features of such electron discharge devices are that the cathode must be capable of producing comparatively large emission currents and close spacing between electrodes must exist to permit advantageous and efficient use of these emission currents. The electrode structures must be such that there exists a minimum capacitance between the electrodes and their leads considering their characteristics. Connections of high conductance and low inductance must be provided between the electrodes of the device and the circuits associated with the device. Interelectrode insulating supports must withstand high voltages and have low losses at the high frequencies. Structural designs must be such as to permit large power and heat dissipation by thermal conduction and radiation. While compact mount assembly is required the design must be such as to facilitate the use of jig assemblies for rapid and accurate assembly of the device. It is also desirable that such devices may be easily disassembled for repairs.

It is therefore an object of my invention to provide an electron discharge device particularly useful at ultra high frequencies and capable of generating comparatively high power.

Another object of my invention is to provide an electron discharge device in which the oathode is capable of providing comparatively large emission currents.

A further object of my invention is to provide such a device having close spacings between electrodes which will enable advantageous use to be made of the emission currents to thereby provide higher operating efliciency.

Another object of my invention is to provide an electron discharge device of the type described having minimum, capacitance between electrodes.

A still further object of my invention is to provide an electron discharge device in which the connections between the electrodes of the electron discharge device and circuits associated therewith are of high conductance and low inductance.

A further object of my invention is to provide such a device in which insulation losses are low at high frequencies and in which the structural design is such as to provide comparatively high power heat dissipation by thermal conduction and radiation.

A further object of my invention is to provide such a device and circuit which is of reasonable size and economical to operate.

A still further object of my invention is to provide a device of the type described in which seals between envelope and leads are facilitated and accuracy of electrode alignment promoted by simple construction permitting the use of accurate jigs for this purpose.

Another object of my invention is to provide such a device in which dismantling of the device is facilitated for repair purposes.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection with the accompanying drawing in which Fig. 1 is a longitudinal section of an electron discharge device made according to my invention; Fig. 2 is a transverse section taken along the line 2-2 of Fig. 1; Fig. 3 is a schematic diagram of an electron discharge device made according to my invention and its associated circuit; Fig. 4 is a longitudinal section of an enlarged detail of Fig. 1.

In accordance with my invention I provide an electron discharge device with an envelope mostly of metal, a portion Ill of which includes the transverse anode block l0. This portion may be cylindrical and is terminated by means of the flanges H and I2 which are sealed to end closure members to be described to provide an evacuated envelope. The transverse section It has extending therethrough chambers or anode cavities I3 and M of cylindrical shape. Positioned within these cavities are indirectly heated cathodes I5 and I6 provided with heaters I! and it as shown in greater detail in Fig. 4. The drumshaped cathodes which may be coated on the outside with the usual electron emitting coatings are supported by tubular leads l9 and 29 having at their upper ends the metallic conducting inserts 2| and 22 provided with the supporting and pinlike leads 23 and 24. One end of the cathode heaters is directly connected to the pins 23 and 2d, and the other end of the leads extends thru apertures 2! and 22 in the inserts 2! and 22 and are electrically connected to the leads 23 and Z4 coaxial with members 19 and 29, and sealed at their ends to the tubular members l9 and 26 by the cup-shaped insulating members 25 and 2%. These tubular members may form with a shorting bar 68 a Lecher wire system connected between the cathodes. The tubular members 19 and 23 extend through and are sealed to'a cup-shaped closure merrber 21 supported and sealed to a collar-like member 28 brazed or welded vacuum tight to the r ng member 29 which cooperates with the flange l2.

To provide a vacuum tight seal between the closure member supporting the cathode and" cat ode leads and the flange I2, I provide a bead or rib 12' extending around the surface of the .flan e .l 2 which is pressed into a metallic gasket 30 preferably of copper so that a diffusion seal results when thebolt members3l are screwed up tight. In order to definitely limit the spacing between the electrode elements I provide a lip 12 cxtendingaround the peripheryof flange l2. With this arrangement it is possible with jigs toaccurately position the cathodes within the anode .cavities during assembly when the other lo ure merr ber cooperating with the flange i l is not in position. The seals for the cathode leads can be made and the jigs then Withdrawn. The process may be repeated -for the vgrid members when the cathodeclosure and-supporting member is removed from theendof :the anode block cylinder.

The grids are supported from the opposite end of the device by means'of asecond closure member cooperatingwiththeflange :l l. A cross member 40 supports the studs ll and 42. Supported from the studs and securedathereto are a pair of grid members35' and 36one-of which is shown in greater detail in Fig.4. As shown each grid com- .prises an inverted cup-shaped member 3'! and a bottom ring 38 between which extends the grid wires 3.9 the endsof which may be welded to the cup 3"! and 'ring38. The'cup-shaped member 3'? is provided with" an aperture through which the screw v43-extends to secure thegnid to the stud i i.

The grids therefore are connected to the terminals of a.-Lecher wire system comprising cross member 49 and studs M, the entire assembly being supported and sealed through the closure member H :by means of the rod a l brazed or screwed up tight, the closure member being limited in longitudinal movement by the lip hi on flange H. The envelope may .be exhausted through thetubular exhaust member 53 sealed vacuum tight by the cup-shaped element .54..

The circuit arrangement utilized with an electron discharge device made according to my invention is disclosed in Fig. 3. The grids 35 and '36 are connected in Lecher wire fashion by means of the supporting and connecting bar All. As described, the cathodes l and 36 are likewise connected into a Lecher wire system by means of the tubular cathode leads I9, 253 and a slidable shorting bar 69. If desired and if necessary, radio frequency currents may be eliminated in the cathode heater leads by tuning these leads in the usual way. The shorting bar 653 may be placed across the ends of the members HQ and 20 and may be moved longitudinally along these tubular members to tune the circuit. A coupling loop 6i may be utilized to extract energy from the device. Cathode'heater current may be supplied by the transformer 52 and anode voltage by means of the voltage source 63, the anodes and voltage source being grounded. Bias on the grids 35 and 36 is provided by means of the bias resistor Ed. The device operates in a push-pull manner.

Because of the large mass of the anode block, heat is quickly conducted from the interior to the exterior of the block where it may be removed either by a cooling medium flowing through a jacket applied to the block or if desired cooling fins and forced air may perform this function.

The small electrode structures reduce interelectrode capacities and inductances and permit operation of the device at ultra high frequencies. Simplicity of construction and assembly facilitates the use of jigs of comparatively simple design and reduces the time required for assembly While at the same time insuring accurate interelectrode spacing. A comparatively large cathode surface emitting area with respect to the size of the grid and anode give a high current to electrode area ratio. High eflicien'ey is promoted due to the close grid cathode spacing permissible by the structural design utilized in a device made according to my invention. These and the other objects noted above in connection with my invention are promoted by an electron discharge device made according to my invention.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the'scope of my invention as set forth in the appended claims.

What I'claim as new is:

1. An electron discharge device including a solid anode block having only a single pair of adjacent separate tubular cavities extending therethrough, a cathode and grid within each of said cavities, said grids being electrically connected together through a common U-shaped conducting support, opposite legs of which are connected to said grids. parallel lines connected to said cathode and oppositely disposed to the grid support, each line being connected to a diiferent cathode, said grid support providing a Lecher wire system, and

to the grid support, said grid support providing a Lecher wire system and said parallel lines being adapted toprovide an oppositely disposed Lecher wire system, a first closure member for one end of said tubular member insulatingly supporting said grid support, and a second closure member for the other end of said tubular member and insulatingly supporting said cathodes and cathode lines.

3. An electron discharge device having a metallic envelope including an anode block member of tubular form having intermediate its ends a comparatively thick transverse partition, said partition having a plurality of adjacent separate tubular cavities extending through said partition and communicating with the spaces within the tubular member only at their ends, a cathode and grid supported within each of said cavities, said anode block member having at one end a transverse flange, and means closing said end of said anode block member including a ring-like member registering with said flange and having an insulating closure element extending thereacross, said cathodes being provided with parallel leads and supports extending through the insulating closure element and sealed therethrough, and means closing the other end of said anode block member and supporting 'said grids, said grids and cathodes being supported independently of each other.

4. An electron discharge device having a metallic envelope including an anode block member of tubular form having intermediate its ends a comparatively thick transverse partition, said partition having a plurality of adjacent cavities extending through said partition, a cathode and grid supported within each of said cavities, said anode block member having at one end a transverse flange, and a first means closing said end of said anode block member including a ring-like member registering withsaid flange and having an insulating closure element extending thereacross, said cathodes being provided with parallel leads and supports extending through the insulating closure element and sealed therethrough, and a second means closing the other end of said anode block member, a grid sup porting structure comprising a conducting element extending transversely of the envelope and electrically and mechanically connected to said grids, the transverse element being provided with a longitudinally extending lead and support sealed through said second means.

5. An electron discharge device having a metallic envelope including an anode block member of tubular form having intermediate its ends a comparatively thick transverse partition, said partition having a plurality of parallel adjacent cavities of cylindrical form extending through said partition and communicating with the space within the anode block only at the ends of said cavities, a cathode and grid supported within each of said cavities, said anode block member being provided with a transverse flange at one end and means closing said end of said block member including a ring-like member registering with said flange and having an insulating closure ele- 'ment extending thereacross, said cathodes being provided with parallel leads and supports ex-" tending through the insulating closure element and sealed therethrough, a grid supporting structure comprising a conducting element extending transversely of the envelope and electrically and mechanically connected to said grids, the transverse element being provided with a longitudinally extending lead and support, and a closure member for the other end of said anode block member and including a plate-like element having a collar-like element extending therefrom the grid lead and support extending through and insulatingly sealed to the collarlike element.

6. An electron discharge device having an anode and a cathode, said cathode including a drum-shaped hollow conducting member coated on the outside thereof, a pin of conducting material extending through and supporting said hollow conducting member and supporting a heater thereon, one end of said heater being connected to said pin and a tubular conducting lead supporting said cathode and having an insert of conducting material connected to and supporting said pin, and a heater lead connected to the other end of said heater and extending coaxially of and within the tubular conducting lead supporting said cathode.

'7. An electron discharge device having an anode block of cylindrical shape and provided with tubular extensions on opposite sides thereof, said cylindrical portion having a pair of cylindrically shaped cavities extending therethrough, a hollow cathode positioned within each of said cavities and a cup-shaped grid positioned over each of the cathodes and between the cathodes and the walls of said cylindrically shaped cavities, a transverse conducting element positioned adj cent said grids and studs extending from said transverse conducting element and connected to and supporting said grids, said transverse conducting element being provided with a longitudinally extending support and lead, said cathodes being provided with parallel leads and supports extending in the opposite direction from the lead and support for said grids, closure members for the ends of said tubular extensions, one of said closure members comprising a plate-like element having a collar-like member extending therefrom, the grid lead and support extending through said collar-like element and insulatingly sealed thereto, and another closure member comprising a ring member supporting a cup-shaped transverse element of insulating material, the cathode" leads and supports extending through and sealed to said cup-shaped element.

8. An electron discharge device having an anode block of cylindrical shape and provided with tubular extensions on opposite sides thereof, said anode block having a pair of cylindrically shaped cavities extending therethrough, a cathode positioned within each of said cavities and a cup-shaped grid positioned over each of said cathodes and between said cathodes and the walls of said cylindrically shaped cavities, a transverse conducting element positioned adjacent said grids and studs extending from said transverse conducting element and connected to and supporting said grids, said transverse conducting element being provided with a longitudinally extending support and lead, said cathodes being provided with parallel leads and supports extending in the opposite direction from the lead and support for said grids, closure members for the ends of said tubular extensions, one of said closure members comprising a plate-like element having a collar-like member extending therefrom, the grid lead and support extending through said collar-like element and insulatingly sealed thereto, and another closure member comprising a ring member supporting a cup-shaped transverse element of insulating material, the cathode leads and supports extending through and sealed to said cup-shaped element, said tubular extensions being provided with transverse flanges, said flanges having a bead extending around the surface thereof, and metallic gaskets positioned between said bead and said closure members, and means forcing said closure members against said gaskets providing a vacuumtightndiffusion seal.

9. An electron discharge device having an anode block of cylindrical shape and provided with tubular extensions on opposite sides thereof, said anode block being provided with a pair of cylindrically shaped cavities extending therethrough, a drum-shaped cathode positioned within each of said cavities, a heater within each of said cathodes and a cup-shaped grid positioned over each of said cathodes and between said cathodes and the Wallsof said cylindrically shaped cavities, av transverse conducting element positioned adjacent said grids and studs extending from said transverse conducting element and connected to and supporting said grids, said transverse conducting element being provided with a longitudinally extending support and lead, said cathodes being provided with parallel leads and supports extending in the opposite direction from the lead for said grids, the cathode leads comprising tubular members, closure members for the ends of said tubular extensions, one of said closure members comprising a plate-like element having a collar-like member extending therefrom, the grid lead and support extending through said collar-like element and insulatingly sealed thereto and the other of said closure members comprising a ring member supporting a cup-shaped transverse element of insulatingmaterial, the cathode leads and supports extending through and sealed to said cup-shaped element, each of said cathode heaters having a lead extending through the tubular cathode lead supporting its cathode.

10. An electron discharge device including a solid anode block having on y a pair of adjacent seperate tubular cavities extending therethrough, a cathode and grid within each of said cavities, said grids being electrically c nnected to eth r h ough a common. U-shaped c nduct ng pport, opposite legs of which are connected to said grids, straight parallel 111165 connected to said cathodes, one lin being connected t each cath d and oppositely disposed to the grid-Support, nd a conducting member extending between said parallel es, said grid support and said parallel lines and conducting member providin o p Sitely d sposed Leoher wire. systems, said cat d and grids be ng supported independent y f each other.

DAVID B, LANGMU R- REFERENCES CITED The ol ngv vr ierelwesare of record in th file of th s patent:

UNITED STATES PATENTS Number Name Date 1,097,552 Kramer .1, -1, May 19, 1914 1,118,380 Stormdr, Nov. 24, 1914 1,264,270 Carpenter Apr. 30, 1918 1,353,976 Stockle Sept. 28, 1920 1,580,855 Prindle Apr. 13, 1926 1,591,432 Noble July 6, 1926 1,817,762 Prince Aug. 4, 1981 2,006,904 Rungeet a1. July 2, 1935 2,086,578 Samuel ,11,-" 1, July 13, 1937 2,108,539 Lindenblad Feb. 15, 1938 2,228,939 ZOttu .etal. Jan. 14, 1941 FOREIGN PATENTS Number I Country Date 265,977 Italy July 13, 1929 

